Semiconductor wafers may be processed in a variety of wet steps to effect cleaning, etching, stripping, coating and other results. Often the chemicals may be caustic or corrosive.
Robots may be utilized to transfer the wafers between various stations and to physically process those wafers at a particular station. The robots, under computer control, allow the wafer fabrication process to be accurately controlled by computer and it is possible to know at every stage where a given wafer is in the process. In addition, the robot can handle heavy wafer batches.
In conventional robotic wet wafer processing operations, the robot includes an arm or end effector which is adapted with fingers. The end effector adapts the robot to semiconductor processing. In particular, the disc-shaped silicon wafers are somewhat delicate to handle and must be treated with care to avoid damaging the wafers. To this end, the wafers are conventionally carried in a carrier with a handle. A number of wafers may be held on edge in the carrier so that all of the wafers in the carrier will receive, at least so long as they are in the same carrier, the same wafer processing.
With robots specially adapted to engage the wafer carriers, the wafer fabrication process can be automated, achieving many of the advantages described above. However, it is necessary that the robot arm carrying the carrier also be exposed to many of the chemical conditions that the wafers themselves are exposed to in the normal course of operation of the robot. The end effectors may be covered by a material that can withstand high temperature, corrosive conditions. If that covering material is scratched, the underlying metal may be subject to corrosive attack. This may require repair of the end effector. This repair may involve re-machining and re-coating.
The arms must be precisely attached to the robot. This is because the robot is programmed to move the arm through desired patterns, assuming the arm is oriented as it was when the arm motion was programmed. Since the orientation of the arm on the robot is adjustable, repositioning the arm after maintenance can be a painstaking process.
Therefore, there is a need for a system which facilitates the maintenance of the end effectors used for the wet wafer processing.